Canadian troops have taken control of a brigade of troops trying to bring peace and security to Afghanistan's war-torn capital, Kabul.

Canada's flag flew above the camp of the Kabul multinational brigade (KMNB) to mark the changeover between German troops and the official entry of the Canadian army into the International Security Assistance Force in Afghanistan.

The job of the brigade - part of the larger Isaf - is to aid the Afghan security forces and provide a secure environment for the re-establishing of community structures in and around Kabul.

Rebels have killed peacekeepers and launched regular attacks against government targets in the area, and have called on Afghans to rid their country of the peacekeepers.

Nato is due to take over command of Isaf, which comprises about 4,600 personnel from 28 countries, on 11 August.

'Dangerous mission'

Nato Secretary-General George Robertson said on Wednesday that the alliance was facing a tough mission in Afghanistan, where military commanders believe anti-government forces could launch attacks.

Peacekeepers are helping to rebuild community structures

"We've already been involved in Bosnia and Kosovo and Macedonia, we're now taking on a role in Afghanistan," Lord Robertson
told reporters after a meeting between Afghan Foreign
Minister Abdullah Abdullah and Nato ambassadors.

"All of these missions have been dangerous and they have been difficult. Afghanistan is certainly no less than that and it may well be one of the toughest that we've taken on."

The UN-mandated force - created in 2001 after the fall of the Taleban - has been under joint German and Dutch command since February.

Under Nato's command it will consist mainly of Canadian soldiers, with Canada contributing about 1,950 troops.

Based on the outskirts of Kabul, the KMNB is made up of around 3,000 soldiers.